Automatic circuit breaker



June 30, 1931. J. SACHS AUTOMATIC CIRCUIT BREAKER Filed April 21, 1928 2 Sheets-Sheet 1 June 30, 1931.

J. SACHS 1,812,842

AUTOMATIC CIRCUIT BREAKER Filed April 21, 1928 2 Sheets-Sheet 2;

Patented June 30, 1931 UNITED STATES PATENT OFFICE JOSEPH SACHS, OF WEST HARTFORD, CONNECTICUT AUTOMATIC CIRCUIT BREAKER Application filed April 21,

The invention relates particularly to a. circuit breaker which is adapted to be small and compact and which is capable of being manufactured at low cost so as to be suitable for use with small motors and household appliances and with service entrance installations. Such a circuit breaker particularly when used in service. entrance installations, may take the place of the usual switch and fuses, and it affords the householder an opportunity of restoring the service himself, after it has been interrupted by an overload, without the necessity for the troublesome replacement of fuses.

It is ordinarily essential that a circuit breaker of this general class shall be trip free, that is, adapted to be automatically operated or tripped independently of the handle so that the circuit breaker will not fail to operate even though the handle be held in closed-circuit position. One of the more general objects of the invention is to provide a circuit breaker of this type particularly adapted for the classes of service referred to and so constructed as to be simple and inexpensive but nevertheless "reliable and ellicient.

In accordance with prior practice the electro-responsive device of a circuit breaker, Whether magnetic or thermal, has acted through interposed links, levers, or other mechanical contrivances to effect the release of the contact carrying member from the control of the handle or actuating member. These interposed connections have not only greatly added to the size and cost of the circuit breaker but they have rendered it less ef fective, particularly in the case of severe overloads or short circuits. These interposed mechanical connections have offered frictional resistance to movement, thus making the circuit breaker less sensitive than it otherwise would be; and by reason of their own inertia and by reason of lost motion in their inter-connections, they have required additional time for their operation, thus delaying the opening of the circuit. In the case of a short circuit, it is necessary, in order to avoid damage tothe circuit breaker itself,"

and toother connected apparatus, to break REISSUED the circuit practically instantaneously. A delay of a very small fraction of a second permits the continued flow of dangerously heavy current, with resultant damage to the connected apparatus. When motion must be transmitted through successively acting mechanical connections, time is lost and the opening of the circuit is delayed.

In accordance with the present invention the delay in the openingof the circuit is very greatly reduced, and is in fact practically eliminated, by utilizing the electro-responsive means or at least the electro-responsive element thereof as a part of the mechanical connection between the actuating member and the contact member. N ormally this element of the electro-responsive means serves as a mechanical connection whereby motion may be transmitted from the actuating member to the contact member; but upon the attainment of abnormal current conditions in the circuit the said element, by reason of its own electro-responsive characteristics, moves in such a way as to render the mechanical connection ineffective and to thereby permit the contact member to independently immediately move to its open-circuit position. This movement of the contact member takes 1928. Sena],- NO. 271,819.

place immediately upon the electro-respon- Y sive movement of the said element without any of the delay heretofore resulting from the transmission of motion through interposed mechanical connections.

A more specific object of the invention is to provide a circuit breaker of the type described wherein the electro-responsive means includes or has associated therewith a thermostatic bi-metallic element serving in and of itself as a part of the mechanical connection between the actuating member and the contact member. This bi-metallic element, by reason of its own inherent thermal- 1y responsive characteristics, is deflected or otherwise moved upon the attainment of abnormal current conditions in the circuit so as to thereby release the contact member for independent movement to open-circuit position.

'.The use of the bi-metallic element as an esused as the electro-responsive means in classes of service where such an element has not heremain insulating base, which base may be utilized to carry other electrical parts.

A still further object of the invention is to provide in a circuit breaker of the type described an. improved body construction including spaced parallel plates upon which the other parts of the circuit breaker proper are supported.

While-as already pointed out the use of the thermostatic bi-metallic element as a part of the connection between the actuating member and the contact member makes it possible to use such an element for classes of service wherein it would not otherwise be acceptable,

it is nevertheless possible that for some spezontal sectional View taken along the line cial or unusual classes of serve'ije it may be necessary or at least desirabl to still further speed up the action. This may be done by comblning with the thermostatic lei-metallic strip a magnetic device which acts to accelerate the thermally responsive movement of the strip. A further object of the invention therefore is to provide a circuit breaker of the type described which includes two electro-responsive devices, one thermal and one magnetic, the two devices being arranged and connected in an improved manner so that either may serve to release the movable contact and open the circuit.

A still further object of the invention is to provide a circuit breaker of the type last above referred to wherein there is a complete circuit breaking unit which includes a thermally controlled element, the said unit being detachably combined with a magnetic mechanism which may serve to release the contact of the said unit.

In the accompanying drawings I have shown two embodiments of the invention but it will be understood that the drawings are intended for illustrative purposes only and are not to be relied upon as limiting or defining the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

Of the drawings:

Fig. 1 is a front view of a circuit breaker embodying the invention, the said circuit breaker being shown as enclosed in a cabinet adapted to be protectively associated with an electric meter.

Fig. 2 is abottom view of the circuit breaker shown in Fig. 1, the enclosing cabinet being shown in transverse section.

Fig. 3 is 'a side view partly in section along the line 3-3 of Fig. 1, the enclosing cabi. net being omitted.

Fig. 4 is a vertical sectional view taken along the said line 33 of Fig. 1, but showing the parts in the positions to which they are moved automatically when an overload occurs. I

Fig. 5 is a horizontal sectional view taken along the line 55 of Fig. 1, but showing the parts in the positions to which they are moved manually for breaking the circuit.

Fig. 6 is an enlarged fragmentary perspective view showing the cooperative relationship of certain parts. i

Figs 7 to 9 are diagrams showing the principle of operation.

Fig. 10 is a front view showing an alternate embodiment of the invention, the cover being omitted.

Fig. 11 is a vertical sectional view taken along the line 11-11 of Fig. 10.

Fig. 12 is a horizontal sectional view taken along the line 1212 of- Fig. 10.

Fig. 13 is an enlarged fragmentary hori- 1313'of Fig. 11.

The circuit breaker proper may, if preferred, constitute a separate unit adapted to be combined or associated with other electrical parts audit will be so describedfi' Referring particularly to Figs. 1 to 6 of the drawings, 1 represents as an entirety the body portion of the circuit breaker unit. The body portionl as illustrated comprises two side plates 2, 2 and two cross bars 3, 3 all formed of insulating material. In addition the .body comprises two transverse U- shaped metallic members 4, 4. In order that the various parts may be held together I have shown screws 5, 5 extending through the bars 3, 3 into the members 4, 4 and I have. shown the said members 4, 4 as provided with integral extensions 6, 6 which extend through openings in the side plates 2, 2 and are riveted over. It will be observed that with the body constructed as described there is provided a central rectangular opening therein bounded at the sides by the plates Ill 2, 2 and at the ends by the bars 3, 3 and the U-shaped members 4, 4.

I provide a manually controllable actuating member for the circuit breaker. I do not narrowly limit myself as concerns the construction and movement of the actuating member but I have shown an actuating member 7 which is movable rectilinearly forward and rearward and extends through the opening in the body. For supporting and guiding the actuating member 7 I provide an additional transverse connecting member extending between the two side plates 2, 2. This additional member is in the form of a U-shaped yoke 8 which is provided with a central opening through which the member 7 is slidably movable. The legs of the yoke 8 extend rearward and engage the side plates 2, 2 being held in place by means of screws 9, 9. Connected with the actuating member 7 at the front end thereof is an operating member or handle 10, this handle being connected by means of a transverse screw 11.

Carried by the body 1 of the circuit breaker unit is at least one relatively fixed electrical contact and preferably two such contacts. I have shown two contacts 12, 12 which project into the central opening of the unit opposite sides thereof, being secured to the bottom flanges of the U-shaped members 4, 4 by means of rivets or screws 13, 13. The rear portions of the contact elements 12, 12 acting in conjunction with the corresponding rear portions of the Ushaped members 4, 4 serves as connectors adapted to be detachably engaged with suitable companion connectors on a main supporting base or panel such as will be described. The said connectors serve to effect not only mechanical connection, but also electrical connection as will presently appear.

The circuit breaker unit includes a movable contact member 14 adapted to be moved in unison with the actuating member 7. This contact member may advantageously be mounted directly upon and carried by the "actuating member and it is so shown. When the actuating member is movable rectilinearly the contact member is preferably also movable rectilinearly. As shown the contact member 14 is in the form of an insulating block provided with a central aperture through which the actuating member 7 extends. The said block 14 is adapted to slide longitudinally of the actuating member being guided in part thereby and in part by the legs of the U-shaped yoke 8. Carried by the block 14 is at least one and preferably two movable contacts 15, 15 these being positioned to respectively engage the fixed contacts 12, 12 when the block 14 is in its normal or rearmost position. The contacts are held in place by means of screws 16, 16 provided with nuts 16*, 16

In conjunction with the said actuating and contact members I provide an electro-responsive means which comprises an element bodily movable with the said members and constituting at least a part of a normally operative mechanical connection between them, the said element normally making it possible for the actuating member to effect the operation of the contact member. The said element is so constructed and s0 related to other parts that it is inherently responsive to abnormal current conditions in the circuit, ordinarily excess current; and by reason of an electro-responsive effect acting directly thereon, the said element is movable relatively to the member which supports it. This relative electro-res'ponsive movement serves to render inefiective the mechanical connection between the actuating member and the contact member, and when the mechanical connection becomes ineffective the contact member is permitted to automatically move inthe circuit opening direction independently of the actuating member. In the preferred form of the invention, not only one element of the electro-responsive means is bodily movable with the actuating and contact members, but the entire electro-responsive means is so movab e.

As concerns the broader aspects of my invention I do not limit myself to an electroresponsive means of any one type, but I prefor an electro-responsive means of the type wherein the electro-responsive action is a thermal one. The electro-responsive means which is shown in the drawings is a bi-metallic thermal element or strip 17 which is carried by the contact member 14 and preferably is electrically connected between the contacts 15, 15.

When so connected,-the strip 17 is adapted to be deflected by reason of the heating action of excess current therein in accordance with the well known action of such bi-metallic strips. 'The. strip 17 is substantially U- shaped as shown and it projects through the central opening in the block 14, being held in place by the nuts 16, 16 on the said'screws 16, 16. The rear transverse portion of the stripl7 extends through a slot 18 in the actuating member 7 and when the strip 17 is at normal temperature the said transverse rear portion thereof is engaged in a notch 19 in the said actuating member 7.

Thus the strip 17 serves in and of itself as a latch for releasably connecting the contact member and the actuating member. Preferably there is a small reinforcement 17*, carried by the thermal strip 17 and constituting a part of the latch, this reinforcement being located at the point where the strip'enters the notch 19. I

It will be noted particularly from an in spection of Figs. 4 and 6 that theend portions of the bi-metallic strip 17 are electrically connected with and preferably directly engage the respective metallic pieces which form the movable contacts 15, 15. The thermal strip is held in such engagement by means of the nuts 16, 16 on the screws 16, 16 and it will therefore be obvious that the thermal strip may be readily removed for adjustment or replacement without removing the contacts themselves from the contact member or block 14 upon which they are carried.

The contact member or block 14 with the movable contacts 15, 15 thereon is biased relatively to the actuating member for movement toward its open circuit position, in this case toward its forward position. Preferaits front end against the said member 14 and abutting at its rear end against a washer 21 carried by the actuating member at the rear end thereof. The washer 21 may have openings therein as shown. The spring 20 tends to move the contact member forward with respect to the actuating member, such forward movement, however, being normally prevented by reason of the engagement of the strip 17 in the notch 19 as already described.

Figs. 7, 8 and 9 are diagrammatic fi ures showing the operation of the device. ig. 7 shows the parts in the normal positionwith the circuit closed; Fig. 8 shows the parts in the position to which they are moved when the circuit is opened manually; and Fig. 9 shows the parts in the position to which they are moved when the circuit is opened automatically.

From the foregoing description, and particularly by reference to Figs. 7 and 8, it will be seen that the entire assembly comprising the actuating member 7, the handle 10 and the contact block 14 together with the immediately associated parts may be moved bodily forward or rearward by means of the said handle 10. With the parts in the rear position as shown imFigs. 2,3 and 7 the contacts 15, 15 are in engagement with the contacts 12,12, a circuit being thus-established which includes the said thermostatic element 17. The circuit may be broken by moving the aforesaid assembly bodily forward to the positons shown in Fig. 8 thus disengaging the contacts 15, 15 from the contacts 12, 12. It will be observed that the circuit is broken at two places thus minimizing any arcing tendency. The transverse portion of the yoke 8 serves as a stop to limit the movement in both directions. 2

As stated the normal circuit through the device includes the bi-metallic strip 17 This strip is so constructed and so mounted that upon the passage of a current therethrough in excess of a predetermined amount it will be deflected toward the left as viewed in Fig.

6. The strip is so constructed and adjustedthat when the current exceeds the said predetermined amount the said strip 17 will disengage the shoulder at the front end of the notch 19 thus breaking the mechanical 5 connection betweenthe contact block 14: and" the actuating memb'rff. As soon as this immediately broken at two places as shown in Fig. ,9.

After the circuit has once been broken by the action of the sprin 20 as already described it may be re-esta lished by first pulling the operating member or handle 10 and the actuating member 7 forward sufficiently to permit the strip 17 to again enter the notch 17 The parts are then in the positions shown in Fig. 8. With the strip thus entered in the notch the circuit may be closed in the usual way by pushing the entire assembly rearward as already described. It will be clear that if the excess current conditions still prevail upon the attempted re-closure of the circuit, the thermostatic strip 17 will again act as already described to break the mechanical connection between the contact member and the actuating member and thus cause the reopening of the circuit. 7

In addition to the spring, such as the spring 20, which serves to bias the contact member for movement to its open circuit position I preferably provide a second spring means which is adapted and positioned to act upon the actuating member independently of the contact member to move both of the members to their open circuit positions when they are connected with each other in the normal manner. When such an additional spring is provided it is obviously necessary to provide a means, preferably manually releasable, adapted to hold the actuating mem her in its closed circuit position and to prevent movement thereof by the said second spring except when the circuit is to be manually opened.

As illustrated the additional spring means comprises two leaf springs 23, 23 which are rigidly mounted at their rear ends on the bodyof the device. Preferably, and as shown, the springs 23,23 are held by the same screws 9, 9 which have already been referred to. The springs 23, 23'are mechanically connected with the actuating member 7 and with the handle 10 by means of toggle links 22, 22. The links 22, 22 extend through slots in the rear portion of the handle 10 and are pivotally mounted at their inner ends on the aforesaid screw 11. The said links are pivotally connected at their outer ends with the said leaf springs 23, 23. It will be-observed that, when the central pivotal axis of the toggle links at 11 is in ront of a line connecting the end pivotal axes, the springs 23, 23 will act tomove the actuating member and handle and also the contact member in the forward direction to their open circuit positions. It will also be observed that, when the pivotal axis at 11 is behind the said line connecting the. end axes, the said toggle links 22, 22 serve as a means for holding the actuating member and handle in their rear closed circuit positions.

' Although the toggle links thus serve to hold the actuating member and handle in their rear positions it will be observed that the said parts are releasably held, being adapted to be moved forward manually at any time. The toggle links and springs serve not only to hold the movable switch parts in their on positions or in their off positions but in addition they serve to effect a quick make and break action inasmuch as the springs augment the manual action, making it much more speedy than would otherwise be the case.

The circuit breaker unit which have described may be used in association with any desired parts and I do not limit myself to any one use thereof. However, in order that one application of the invention may be clearly understood I have shown the said unit combined with other parts to form a house entrance installation adapted to be directly associated with an electric meter M. I do not herein broadly claim the use of an automatic circuit breaker mechanism as a part of a meter service installation this be- .ing set forth and claimed in my patent for electric service installation No. 1,696,150, dated December 18, 1928.

I have shown the circuit breaker unit as mounted on a base 24 of insulated material. The said base is provided with conducting plates 25 and 26 which are held in place on the base by means of screws 27, 27 extending forward from the rear thereof. The said plates 25 and 26 constitute connectors adapted to be engaged by the aforesaid connectors at the rear of the circuit breaker unit. The circuit breaker unit proper is held in place with the respective connectors in engagement by'means of screws 28, 28 which extend through holes in the. lower flanges of the members '4, 4 and into threaded holes in the said plates 25'and 26. The said plates 25 and 26 are further provided with means such as the screw 29 and the clamp 30 for engagement with electric conductor wires. In order that complete provision may be made for the connection and use of an electric meter I provide on the base 24 in addition to the circuit breaker unit a neutral conductor or strap 31- provided with wire terminals 32 and 33 and a test switch 34 interposed between wire terminals 35 and 36. The details of the test switch ,34 may be varied ut I have shown a switch comprising a bla e 37 pivoted at 38 and adapted to be swung laterally by means of an insulating handle 39. In order to further-facilitate the testing of the meter suitable contacts adapted for the attachment of instrument leads and by-pass connections are provided at 40, 40.

One arrangement of electrical connection which ma be used is shown by dot-and-dash lines in Fig. 1. The service wires S are cononly the customers load circuit but also the meter in case of any excess current conditions. The circuit from the meter extends through the test switch 34'and this switch may therefore be utilized to disconnect the meter from the load wires for testing in accordance with well understood practice. Prior to the opening of the switch 34 a suitable by-pass may be connected to the proper contacts 40, 40 in order that the customers circuit may not be interrupted.

The base 24 and the parts carried thereby may be enclosed in a protecting cabinet such as the cabinet 41. This cabinet is or may be of substantially standard construction being rectangular in form and having an openable front cover 42 adapted to be sealed in closed position to protect the 1nterior parts. The base 24 may be secured to the rear wall of the cabinet by means of screws 24*, 24*. Preferably the upper end wall 43 of the cabinet is provided with a suitable opening through which the terminal chamber portion of the meter may pro ect as shown so as to entirely enclose the connections between the meter and the service appliance within the cabinet. The front cover 42 of the cabinet is provided with an opening 44 through which the handle 10 projects. It will be seen that this arrangement permits the customer to operate the circuit breaker without obtaining access to the interior of the cabinet. By means of the operating member or handle 10 the customer can operate the circuit breaker to open and close the circuit for normal switching purposes or he can operate it to close the clrcuit after it has been automatically opened as the result of an overload.

In Figs. 10 to 13 I have shown another embodiment of the invention mcluding a circuit breaker unit which is or may be exact; ly the same in construction as that already fully described. The circuit breaker umt is designated as an entirety by U, and it may be I 48, 48 extending from the back of the base.

The plate 46 is provided with a screw 49 adapted to serve as a wire terminal.

I provide in association with the self contained circuit breaker unit U means supplemental thereto for mechanically efiecting the operation thereof, the said supplemental means being electrically controlled preferably magnetically. The said supplemental. means may be mounted on the same base 45 which supports the circuit breaker unit U and I have so shown it in the drawings. ll do 10 not herein broadly claim a circuit breaker adapted to operate by the combined or alternative electro-thermal and electro-magnetic effects of the current, as this subject matter is set forth and claimed in my patent for automatic circuit breaker, No. 1,736,372

issued November 19, 1929.

As illustrated the base 45 carries a rock shaft 50 which is located directly behind the circuit breaker unit and extends perpendicularly to the axis thereof. The shaft 50 is supportedby suitable bearing members 51 and 52 the former being held in place by a screw 53 and the latter being molded in place in the material of thecbase. The rock shaft carries at least one and preferably two pins 54, 54 which normally project through an opening in the washer 21 and are located in close proximity to the lower portion of the (bi-metallic strip 17. Associated with the shaft 50 is a spring 55 which tends to rotate the shaft in the clockwise direction as viewed in Figs. 9 and 10, that is, in the direction to move the pins 54, 54 away from the bimetallic strip 17. Carried by the shaft 50 36 near one end thereof is a member. 56 adapted to serve as a magnetic armature. As shown the shaft 50 has a right angle bend near its lower end, the member 56 being carried by the angularly' extending portion 57.

Carried by the base 45 is an electro-magnet 58 comprising a coil 59 and pole pieces 60, 60 connected with a suitable core. The magnet is supported by a bracket 61 of nonmagnetic material held in place by the afore- 46 said screw 53 and another screw 62. One

end of the wire forming the coil 59 is connected with the terminal plate 47 and the other end is connected with a terminal plate 63 secured to the base and provided with a screw 64 forming a main wire terminal.

The incoming and outgoing wires are connected respectively with the terminals 64 and 49 and thus the magnet 58 and the circuit breaker unit U are connected in series with each other.

Upon the passage of excess current the bimetallic strip 17 of the circuit breaker unit 1 tends to act in the way already described to effect the opening of the circuit. How- 80 ever, inasmuch as the magnet 58 is in series with the circuit breaker unit the said magnet is simultaneously energized tending to draw the armature 56 upward between the pole pieces 60, 60. Movement of the armature 56 65 rocks the shaft'50 in the counter-clockwise U as shown in Figs. 10 to 13, the thermostatic bi-metallic element may be designed and proportioned to act somewhat more slowly, and in this case the parts are so constructed and adjusted in relation to each other that a moderate overload will cause the bi-metallic strip 17 to deflect and effect the opening of the circuit as already described, without energizing the magnet sufficiently to enable it to be effective. However, in the case of an excessive overload such as might be caused by a short circuit the magnet will be instantly energized thus rocking the shaft 50 and releasing the strip 17 from the operating member by direct mechanical engagement therewith. In the case of an excessive overload the magnet would act more quickly than the bi-metallic strip and thus the circuit would be interrupted more quickly than it would by means of the normal action of the bi-metallic strip.

The construction as shown inFigs. 7 to 10 may be enclosed by means of a suitable cover if desired, such a cover being shown at 65. The cover 65 is held in place by means of screws 66, 66 projecting into holes in the base 45. The cover 65 is provided with an opening 67 for the handle 10. Screws 45, 45 may be provided for mounting the en- 'tire device on a wall or panel. Wires may' extend from the rear through the wall orpanel and through holes 64 and 49 in the base into engagement with the terminals 64 and 49.

What I claim is:

1. An automatic circuit breaker comprising in combination, a movable contact member biased toward its open-circuit posit-ion, a movable actuating member normally adapted to move the contact member to open or close the circuit, and an electro-responsive means comprising an element inherently responsive to abnormal current conditions in the circuit and constituting at least a part of a mechanical connection between the said actuating and contact members normally operative to prevent independent circuit opening-movement of the latter, the said .element upon the attainment of an abnormal current condition in the circuit being relatively movable by reason of its own inherent electro-responsive characteristics so as to render the said mechanical connection ineffective and to thereby permit the contact member to move to its open-circuit position independently of the actuating member.

2. An automatic circuit breaker as set forth in claim 1, wherein the electro-responsively movable element is a latch carried by one of the said members and normally having a direct engagement with the other, the said latch being automatically disengaged from the said other member upon the attainment of an abnormal circuit condition so as to permit independent movement of the contact member.

3. An automatic circuit breaker as set forth in claim 1, wherein the entire electro responsive means is bodily movable with the said actuating and contact members.

4. An automatic circuit breaker as set forth in claim 1, wherein there are two sep-- arate circuit breaking contacts on the contact member and wherein the entire electroresponsive means is bodily movable with the said member and is electrically connected between the said contacts.

'5. An automatic circuit breaker as set forth in claim 1, wherein the actuating and contact members are normally movable in fixed relationship with each other and wherein the entire electro-responsive means -is bodily movable with the said actuating and contact members. 1 7

6. An automatic circuit breaker comprising in combination, a movable contact member biased toward its open-circuit position, a movable actuating member normally adapted to move the contact member to open or close the circuit, and an electro-responsive means comprising a thermally-responsive element normally movable with the said actuatiiig and contact members and constituting at least a part of a mechanical connection between them normally operative to prevent independent circuit opening move ment of the contact member, the said element upon the attainment of an abnormal current condition in the circuit and as the result of its own thermally-"responsive characteristics being movable relatively to the said actuating andcontact members so as to render the said mechanical connection ineffective and to thereby permit the contact member to move to its open-circuit position independently of the actuating member.

'7. An automatic circuit breaker as set forth in claim 6, wherein the thermally-responsive element is a latch carried by one of the said members and normally having a direct engagement with the other, the said latch being automatically disengaged from the said other element upon the attainment of an abnormal current condition.

8. An automatic circuit breaker as set forth in claim 6, wherein the contact member is carried by and is normally movable in unison with the actuating member, and wherein the thermally-responsive element is a latch carried by one of the said members and normally having a direct engagement with the other, the said latch being automatically disengaged from the said other element upon the attainment of an abnormal current condition.

9. An automatic circuit breaker comprising in combination, a movable actuating member, a movable contact member biased toward its open-circuit position, and an electro-thermally affected element serving in and of itself as a releasable latch normally movable with the actuating and contact members and normally operative for mechanicall connecting them to enable the former to e ect the movement of the latter to open or close the circuit, the said electrothermally affected latch being connected in the circuit so as to be automatically actuated upon the passage of excess current therethrough to mechanically disconnect the contact member from the actuating member and thus permit the said contact member to automatically move to its open-circuit position independently of the actuating member.

10. An automatic circuit breaker as set forth in claim 9, wherein the electro-thermal latch is carried by the contact member and is movable therewith independently of the actuating member.

11. An automatic circuit breaker comprising in combination, a movable contact member biased toward its open-circuit position, a movable actuating member normally adapted to move the contact member to open or close the circuit, and a thermostatic bi-metallic stripserving in and of itself as a releasable latch normally movable with the actuating and contact members and normally operative for mechanically connecting them to enable the former to efi'ect the movement of the latter, the said thermostatic bi-metallic latch being connected in the circuit so as to be automatically deflected from its normal position upon the attainment of an abnormal current condition in the saidcircuit and to thus mechanically disconnect the contact member from the actuating member and permit the said contact member to automatically move to its open-circuit position independently of the actuating member.

12. An automatic circuit breaker as set forth in claim 11, wherein the thermostatic bi-metallic latch is so related to the actuating and contact members that it acts by tension to move the contact member to closed-circuit position and to normally hold it in such 'position. i

13. An automatic circuit breaker comprising in combination, a movable actuating member, a movable contact member biased toward its open-circuit position, two contacts on the contact member, two stationary contacts with which the movable contacts are normally engaged, and a bi metallic strip serving in and of itself as a releasable latch normally movable with the actuatin and contact members and normally operative for mechanicallyconnecting them to enable the former to efl'ect the movement of the latter to bring the movable contacts out of or into engagement with the respective stationary contacts and thereby open or close the circuit at two separate places, the said bi-metal licstrip being carried by the contact member so as to be movable therewith independently of the actuating member and being electrically connected in the circuit between the two movable contacts so as to be automatically deflected upon the passage of excess current therethrough to mechanically disconnect the contact member from the actuating member and thus permit the said contact member to automatically move to its open-circuit position independently of the actuating member.

14. An automatic circuit breaker as set v forth in claim 13, wherein the thermostatic bi-metallic strip is U-shaped and wherein the end portions of the strip aredetachably held in electrical connection with the respective movable contacts.

'15. An automatic circuit breaker as set forth in claim. 13, wherein the thermostatic bi-metallic strip is U-shaped, and wherein there are provided devices accessible from the front of the circuit breaker and serving to detachably hold the end portions of the strap in electrical connection with the respective movable contacts.

16. An automatic circuit breaker comprising in combination, a movable actuating memher, a movable contact member, a spring operatively interposed between the actuating member and the contact member and tending to move the latter relatively to the former toward its open-circuit position, and movablemeans providing a normally operative releasable mechanical connection between the actuating member and the contact member enabling the former toeifect the movement of the latter to open or close the circuit, the said connection means including an electroresponsive device normally movable with the said actuating and contact members and elec trically connected in the circuit so as to automatically serve upon the passage of excess current to release the contact member from the actuating member and thus permit the said contact member to automatically move under the action-of the spring to its open circuit position independently of the actuating member. p I

17. automatic circuit breaker as set forth in claim 16-, wherein the contact member and the spring are both carried by the actuating member. 18. An automatic circuit breaker comprising in combination, two stationary electrical contacts spaced apart, a contact memberof insulating material rectilinearly movable beamaze 1 tween the stationary contacts and biased tor movement in the circuit opening position, two movable contacts on the contact member in electrical connection with each other and from the actuating member and thus permit 7 the said contact member to automatically move rectilinearly to its open-circuit position independently of the actuating member.

19. An automatic circuit breaker compris-' ing in combination, a rectilinearly movable actuating member, a contact member rectilinearly movable longitudinally of the actuating member and biased toward its opencircuit position, and movable means providing a normally operative releasable mechanical connection between the actuating member and the contact member enabling the former to effect the rectilinear movement of the latter to open or close the circuit, the said connection means including an electro-responsive device normally movable with the said actuating and contact members and electrically connected in the circuit so as to automatically serve upon the passage of execs current to release the contact member from the actuating member and thus permit the said contact member to automatically move rectilinear-1y to its open-circuit position lndependently of the actuating member.

20. An automatic circuit breaker comprising in combination, a rectilinearly movable to mechanically disconnect the contact member from the actuating member and thus permit the said contact member to automatically move rectilinearly to its open-circuit posi tion independently of the actuatin member.

21. An automatic circuit brea or comprising in combination, a fixed electric contact, an actuating member manually movable rectilinearly, a contact member movable longitudinally of the actuating member and havin an electric contact movable into or out o? engagement with the fixed contact, a spring operatively interposed between the actuating member and the contact member and tending to move the latter relatively to the former so as to bring the movable contact out of engagement with the fixed contact, and means including an electro-responsive device normally movable with the actuating member and normally serving to prevent the said relative movement of the movable contact member by the spring, the said electro-responsive device being electrically connectible with the contacts and serving upon the passage of ex cess current to release the contact member and thereby permit the said relative movement thereof by the spring.

22. An automatic circuit breaker comprising in combination, two fixed electric contacts, an actuating member manually movable rectilinearly, a contact member provided with two electric contacts and movable longitudinally of the actuating member to bring the contacts into or out of engagement with the respective fixed contacts, a spring operatively interposed between the actuating member and the contact member and tending to relatively move the contact member in the direction of disengagement, and electroresponsive thermal strip mounted on the contact member and electrically connected between the contacts thereof, the said strip normally serving as a latch to engage the actuating member and prevent the said relative movement of the contact member by the spring and serving upon the passage of excess current to release the movable contact member and thereby permit the said relative movement thereof by the spring.

23. An automatic circuit breaker comprising in combination a body having a centra opening, fixed electric contacts on the body at opposite sides of the opening, an actuating member manually movable rectilinearly through the body opening, a yoke carried by the body and engaging the actuating memher to guide it, a contact member provided with two electric contacts and movable through the body opening longitudinally of the actuating member to bring the contacts into or out of engagement with the respective fixed contacts, a coil spring carried by and surrounding the actuating member and tending to move the contact member in the outward direction to effect disengagement of the contacts, and an electroresponsive thermal strip mounted on the contact member and electrically connected between the contacts thereof, the said strip nor- 7 mally serving as a latch to engage the actuating member and prevent the said relatlve movement of the contact member by the spring and serving upon the passage of excess current to release the movable cont-act member and thereby permit the said relative movement thereof by the spring.

24. An automatic circuit breaker comprising in combination, a movable actuatin member, a movable contact member biase relatively to the actuating member for movement toward its open-circuit position, movable means providing a normally operative releasable mechanical connection between the actuating member and the contact member enabling the former to effect the movement of the later to open or close the circuit, the said connection means including an electro-responsive device normally movable with the said actuating and contact members and electrically connected in the circuit so-as to automatically serve upon the passage of excess current to release the contact member from the actuating member and thus permit the said contact member to automatically move to its open-circuit position independently of the actuating member, a pair of toggle links serving in one position to hold the actuating member in its closed-circuit position, and a spring means serving when the toggle links are moved from their said holding position to automatically move both the actuating member and the contact member to their open-circuit positions.

25. An automatic circuit breaker comprising in combination, a fixed electric contact, an actuating member manually movable rectilinearly, a contact member movable longitudinally of the actuating member and having an electric contact movable into or out of engagement with the fixed contact, a spring tending to move the contact member relatively to the actuating member to bring the movable contact out of engagement with the fixed contact, means including an electroresponsive device bodily movable with the l contact member and normally serving to prevent the said'relative movement of the contact member by the spring, thesaid electroresponsive device being electrically connectible with the contacts and serving upon the passage of excess current to release the movable contact member and thereby permit the said relative movement thereof, and spring pressed toggle links having their inner ends connected with the actuating member, the said toggle links when in one position tending to hold the actuating member and associated parts in their inner positions and when in another position tending to hold the actuating member and associated parts in their outer positions.

26. An automatic circuit breaker comprising in combination a body having a central opening, fixed electric contacts on the body at op osite sides of the opening, an actuating mem er manually movable rectilinearly through the body opening, a contact member provided with two electric contacts and movable through the body opening longitudinally of the actuating member to bring the movable contacts into or out of engagement with the respective fixed contacts, a spring tending to move the contact member relatively to the actuating member to efiect disengagement of the contacts, means including an elecinner ends connected with the actuating member, and leaf springs carried by the body and engagin the outer ends of the toggle links, the sai springs causing the toggle links when in one position to hold the actuating member and associated parts in their inner positions and causingthe to gle links when 1n another position to hol the actuating member and associated parts in their outer positions.

27. An automatic circuit breaker compr1su I o 0 mg in combinatlon, a movable actuatin member, a movable contact member biase toward its open-circuit position, movable means providing a normally operative releasable mechanical connection between the actuating member and the contact member enabling the former to efiect the movement of the latter to open or close the circuit, the said connection means including an electro-responsive device normally movable w1th the said actuating and contact members and electrically connected in the circuit so as to automatically serve upon the passage of excess current to release the contact member from the actuating member and thus permit the said contact member to automatically move to its open-circuit position independently of the actuating member, and a second electroresponsive device connected in the circuit and held against bodily movement with the said actuating and contact members, the second said electro-responsive device being positioned to act upon a portion of the normally operative releasable mechanical connection and serving upon the passage of excess current to relatively move the said connection matically move as aforesai and thereby release the contact member from the actuating member" to (permit it'to auto- 28. An automatic circuit breaker comprising in combination, a fixed electric contact,

tively to the actuating member so as to bring the movable contact out of engagement with the fixed contact, an electro-responsive thermal strip normally movable with the actuating member and normally serving as a latch to prevent the said relative movement of the movable contact member by the spring, the said strip serving upon the passage of excess current to release the contact member and thereby permit the said relative movement thereof by the spring, and magnetically controlled means acting upon the said strip to move it and thereby release the movable contact member upon the passage of excess current.

29. An automatic circuit breaker comprising in combination, a fixed electric contact,

a movable contact member having an electriccontact thereon, a manually movable actuating member for moving the contact member to bring the movable contact into or out of engagement with the fixed contact, a spring operatively connected between the actuating member and the contact member and tending to move the latter relatively to the former so as to bring the movable contact out of engagement with the fixed contact, an electro-responsive thermal strip normall movable with the actuating member an normally serving as a latch to prevent the said relative movement of the movable contact member by the spring and serving upon the passage of excess current to release the coiitact member and thereby permit the said relative movement thereof by the spring, and magnetically controlled means engaging the said strip to mechanically move it and thereby release the movable contact member upon the passage of excess current.

30. An automatic circuit breaker mechanism comprising in combination two units detachably connected with each other, one unit comprising a movable actuating member and a movable contact member biased' toward its open-circuit position, together with movable means providing a normally operative releasable mechanical connection between the actuating member and the contact member enabling the former to effect.

circuit so as to automatically serve upon the passage of excess current to releasethe contact member from the actuating member and thus permit the said contact member to automatically move to its open-circuit position independently of the actuating member, and the other unit comprising a magnetically controlled trip means so positioned, when the units are connected, as to engage the releasable mechanical connection of the first unit and thereby release the movable contact member upon the passage of excess current through the trip means.

31. An automatic circuit breaker unit comprising a movable actuatin member, a movable contact member biase toward its opena said actuating and contact members and electrically connected in the circuit so as to automatically serve upon the passage of excess current to release the contact member from the actuating member and thuspermit the said contact member to automatically move to its open-circuit position independently of the actuating member, in comination with a base on which the circuit breaker unit is detachably mounted, and a magnetically controlled trip means on the base so positioned with respect to the releasable mechanical connection of the circuit breaker unit that the said eans can engage the said connection to re ease the movable contact member upon the passage of excess current through the trip means.

32. The combination of a base, a magnetically controlledtrip means on the base, and an automatic circuit breaker unit detachably mounted on the base and comprising a fixed electric contact, a movable contact member having an electric contact thereon, a manually movable actuating member for moving the contact member to bring the movable contact into or out of engagement with the fixed contact, a spring tending to move the contact member relatively to the actuating member to bring the movable contact out of engagement with the fixed contact, an electro-responsive thermalstrip normally movable with the actuating member and normally serving as a latch to prevent the said relative movement of the movable contact member h the spring and serving upon the passage ohexcess current to release the contact member and thereb permit the said relative movement thereo by the spring, the said unit being so positioned with relation to the trip means that the later can enga e the bi-metallic strip of the former to mec anically move it and thereby release the movable contact member upon the passage of excess current through the trip means.

In testimony whereof I have hereunto set my hand this 19th day of April, 1928.

' JOSEPH SACHS. 

